package cn.signalpha.common.utils;

import cn.signalpha.core.tool.utils.StringUtil;

import java.util.Random;

/**
 * 推荐码生成工具
 */
public class ShareCodeUtil {

	private static final char[] r=new char[]{'8','2','9','7','5','3','4','6','1'};

	/** 定义一个字符用来补全邀请码长度（该字符前面是计算出来的邀请码，后面是用来补全用的） */
	private static final char b = '0';

	/** 进制长度 */
	private static final int binLen = r.length;

	/** 邀请码长度 */
	private static final int s = 7;

	/**
	 * 根据ID生成随机码
	 */
	public static String idToShareCode(long id) {
		char[] buf=new char[32];
		int charPos=32;

		while((id / binLen) > 0) {
			int ind=(int)(id % binLen);
			buf[--charPos]=r[ind];
			id /= binLen;
		}
		buf[--charPos]=r[(int)(id % binLen)];
		String str=new String(buf, charPos, (32 - charPos));
		// 不够长度的自动随机补全
		if(str.length() < s) {
			StringBuilder sb=new StringBuilder();
			sb.append(b);
			Random rnd=new Random();
			for(int i=1; i < s - str.length(); i++) {
				sb.append(r[rnd.nextInt(binLen)]);
			}
			str+=sb.toString();
		}
		return str;
	}

	/**
	 * 根据随机码生成ID
	 */
	public static long shareCodeToId(String code) {
		code = StringUtil.subSuf(code, 1);
		char[] chs = code.toCharArray();
		long res=0L;
		for(int i=0; i < chs.length; i++) {
			int ind=0;
			for(int j=0; j < binLen; j++) {
				if(chs[i] == r[j]) {
					ind=j;
					break;
				}
			}
			if(chs[i] == b) {
				break;
			}
			if(i > 0) {
				res=res * binLen + ind;
			} else {
				res=ind;
			}
		}
		return res;
	}

	public static void main(String[] args) {
		String s = idToShareCode(57075);
		System.out.println(s);
		long id = shareCodeToId(s);
		System.out.println(id);
	}

}
